Synthesis, structural and dielectric studies of magnetoelectric lead nickel niobate ceramics

Abstract

Synthesis and structural and dielectric studies of lead nickel niobate ceramics with molecular formula PbNi_1/3Nb_2/3 O₃ (PNN) were investigated. The synthesis of PNN powder has been undertaken employing two distinct methods as (i) single step, involving mixing of stoichiometric amounts of the reactants in a single step, and (ii) double step, in which the intermediate binary oxide is prepared first and thereafter in an additional step ternary oxide is formed. It is a challenge to synthesize PNN as single phase by single step even with the addition of excess amount of lead oxide. Single phase of PNN has been successfully synthesized employing double step by adding 2 wt% excess PbO to the stoichiometric amounts of reactants. The PNN crystallizes in perovskite phase with cubic crystal structure with a lattice constant a = 4.0305(2) Å, which confirms with literature data. In this study, the dielectric constant at T = 161.58 K. and 1 kHz frequency is found to be 3384.25. The critical exponent and diffuseness parameter were found to be γ ~ 1.8 and δ ~ 94.24 from the dielectric data.